Q&A Topic: Can Birth Control Pills Give You Breast Cancer?

Elisa E. Burns, MD, FACOG

Women who have used birth control pills or hormonal contraceptive devices have a 20% higher risk of breast cancer than women who have not, according to a recent Danish study. The nationwide study followed 1.8 million women aged 15 to 49 for more than 10 years.

Q. Does this mean that the new birth control pills can cause breast cancer?

A. This study shows an association, but not a cause. For a long time, hormonal contraceptives were associated with increased risk of breast cancer. So newer contraceptives have been made with a lower dose of hormones, under the assumption that less is better. According to the study, both estrogen and progesterone—which are used in birth control bills and some IUDs—are associated with breast cancer even in lower doses, though we don't know in what way.

But the study wasn’t adjusted for things we know increase breast cancer risk: Did these women have a family history of breast cancer? Did they breastfeed? Did they consume alcohol? Were they physically active? The study didn’t answer those questions.

Q. Are birth control pills and hormonal IUDs safe for all women to use?

A. For young women who don’t smoke and don’t have a family history of breast cancer, hormonal contraceptives are very safe. The increased risk of breast cancer is very small, and hormonal contraceptives have a lot of benefits—they decrease the risk of uterine and ovarian cancers, for example. The study suggests—but again, doesn’t prove—that the risk is more significant the older you are. So if you're in your mid-40s and you’ve completed childbearing, you might consider having a tubal ligation, or your husband having a vasectomy. Those are not hormonal, though of course they have other risks because they’re surgical.

Q. Is any type of contraceptive risk-free?

A. You might say that condoms and diaphragms are risk-free as they’re not hormonal and not permanent devices. But those are barrier methods, and they have a much higher failure rate. Pregnancy has risks, and terminating your pregnancy has risks. In essence, there is no life without risk. All these choices will impact you in different ways. Women must decide for themselves what risk they could bear.

Q. What’s the main takeaway from this study?

A. We still don’t know exactly what the relationship is between hormonal contraception and development of breast cancer. The study said that there’s an additional 13 cases of breast cancer for every 100,000 people; for women under 35, it is two additional cases. Those are very, very low numbers. This is an important study for research and public health, but it’s not meant to tell women what to do. It’s much more complicated for an individual. At your annual visit to the gynecologist, you should discuss your individual risk, what you’re most concerned about, and where you are in life and in family planning. It’s something to think about, but it’s not an emergency in any way.